Card Range To Study

77 Cards in this Set

Volume of air that enters and leaves the lung in a single cycle. 500ml

Functional residual capacity

Amount of air in the lungs after passive expiration. 2,700ml

Inspiratory capacity

Maximal volume of gas inspired from FRC. 4,000ml

Inspiratory reserve volume

Air that can be inhaled after normal inspiration. 3,500ml

Expiratory reserve volume

Air that can be expired after a normal expiration. 1,500ml

Residual volume

Air in the lungs after maximal expiration. 1,200ml

Vital capacity

Maximal air that can expired after maximal inspiration. 5,500ml

Total lung capacity

Air in the lungs after maximal inspiration. 6,700ml

Total ventilation

Total ventilation = Tidal volume X respiratory rate.

Dead space

Regions that contain air but do not exchange O2 and CO2

Anatomic dead space

Conducting zones. Approximately equal to person't weight in pounds.

Alveolar dead space

Alveoli with air but without blood flow

Physiologic dead space

Anatomic dead space plus alveolar dead space

Alveolar ventilation

Tidal volume - anatomic dead space X respiratory rate.

Lung recoil

Force that collapses the lung. As the lung enlarges, recoil increases and vice versa.

Intrapleural pressure

Normally -5 cmH2O. Force that expands the lung. The more negative, the more lung expansion.

Lung mechanics before inspiration

Glotis is open but no air is flowing - alveolar pressure = 0. Intrapleural pressure and lung recoil are equal but opposite. Gravity decreases intrapleural pressure at the apex and increases it at the bases. Apex alveoli are more distended.

Intrapleural pressure and recoil are the same but opposite. Alveolar pressure returns to zero and air stops flowing in.

Lung mechanics during expiration

Diaphragm relaxes, intrapleural pressure increases, lung recoil collpases the lung. Alveoli compress tha air and alveolar pressure becomes positive and air flows out of the lungs until alveolar pressure is back to zero. Lung recoil and intrapleural pressure become equal but opposite.

Assisted control mode ventilation

Inspiration is initiated by the patient or the machine if no signal is detected.

Positive end-expiratory pressure

Does not allow intraalveolar pressure to return to zero at the end of expiration. The larger lung volume prevents atelectasis.

What is lung compliacnce?

It's the change in volume with a change in pressure. Increased compliance means more air flows in with a given change in pressure. Decreased compliance means the opposite. The steeper the slope of the lung inflation curve, the greater the compliance. Emphysema = very compliant; fibrosis = not compliant.

Apneustic center in the caudal pons promotes prolonged inspiration. Pneumotaxic center in the rostral pons inhibits apneustic center. Efferents are from the medulla to the phrenic nerve (C1-C3) to the diaphragm

Differences in ventilation between the base and the apex of the lung

Base intrapleural pressure is -2.5, alveoli are compliant and small with a small volume of air but are underventilated due to too much blood flow; Apex pressure is -10, alveoli are large and stiff and contain a large volume of air but are overventilated due to limited blood flow

Differences in blood flow between the base and the apex of the lung

Blood vessels of the apex are less distended, have more resistance and receive less blood flow. Blood vessels of the base are more distended, have less resistance and receive more blood flow

Ventilation/perfussion relationship at the base of the lungs

Blood flow is higher than ventilation, the relationship is less than 0.8; the bases are underventilated, ↑ shunts

Ventilation/perfussion relationship at the apex of the lungs

Blood flow is lower than ventilation, the relationship is more than 0.8; the apex are overventilated, ↑ dead space

What does a ventilation/perfussion relationship under and over 0.8 mean?

Under 0.8 (at the bases) lungs are underventilated and less gas exchange takes place, therefore PACO2 and end-capillary PCO2 will be higher and PAO2 and end-capillary PO2 will be lower.

What is hypoxic vasoconstriction?

A decrease in PAO2 causes vasoconstriction and shunting of blood through that segment.

What is the effect of a thrombus in a pulmonary artery?

Blood flow decreases, therefore ↑ Va/Q --> ↓ PACO2, ↑ PAO2

What is the effect of a foreign object occluding a terminal bronchi?

Ventilation decreases, therefore ↓ Va/Q --> ↑ PACO2, ↓ PAO2

What constitutes a pulmonary shunt?

Regions of the lung where blood is not ventilated. Low Va/Q relationship.

What constitutes alveolar dead space?

Regions of the lung where there's no blood flow in spite of ventilation. High Va/Q relantionship